Pseudomugil sp. red neon

Understand what the genus-level name means

The Red Neon Blue-Eye (Pseudomugil sp. red neon) is a freshwater fish in the family Pseudomugilidae. The accepted genus Pseudomugil is endemic to Australia and New Guinea, where its members occur in freshwater rivers and streams as well as bodies of brackish water. It suits a keeper prepared to maintain a mature biological filter, keep a social group of at least five and provide open swimming room alongside cover. WoRMS places Pseudomugil in Pseudomugilidae and the order Atheriniformes.

The abbreviation “sp.” means that the name stops at genus level rather than assigning one species. Do not borrow an adult length, narrow water target or fixed temperament from the profile of a named Pseudomugil species. Use the group ranges and practical safeguards below, then retain enough aquarium capacity to adapt the setup as the fish develops.

Wikipedia’s Pseudomugil summary gives the genus-level distribution and habitats described above. Those habitats explain why the name can cover fish associated with both fresh and brackish waters, while this offer is for a freshwater aquarium fish.

Plan around the complete social group rather than one small individual. A mature filter, zero ammonia, zero nitrite, stable water and gradual stocking are the foundations of the setup. Plants or suitable ornaments provide cover, while an unobstructed area preserves the swimming room described in the rainbowfish guidance.

Read the offer before choosing your fish

One purchase supplies one animal.

The exact species has not been identified, so the care advice here follows the genus Pseudomugil and its care group.

If you want to compare this fish with other members of the wider group, browse our rainbowfish collection without assuming that different products share an adult size or identical care needs.

Sex is guaranteed only when the selected option explicitly states male or female. This Pseudomugil sp. red neon listing has no sex-guaranteed option.

The gallery images are representative, based on reference photographs of this kind of animal, so colours can look slightly different from the live animal.

Make the purchase decision from the identity, group requirement and aquarium plan rather than treating colour, fin shape or apparent sex in a representative scene as a promise about the individual supplied.

Make the main care decisions before purchase

OATA’s rainbowfish guidance gives 22–27°C, pH 6.5–8.0 and 4–12°dH as broad group values; use them as the working range rather than a species-specific optimum. It also gives carbonate hardness of 3–10°dKH, zero ammonia, zero nitrite and nitrate no more than 20 mg per litre above the normal tap-water level.

Check whether the plan fits

OATA uses at least 45 litres for a shoal of its smallest rainbowfish and at least 120 litres for species over 8 cm. Because this genus-level name carries no adult-size category, use at least 120 litres as the cautious planning benchmark. Aquarium dimensions, the intended group and existing occupants all affect the final decision.

Hold the water within a stable working range

Set the aquarium within 22–27°C, pH 6.5–8.0, general hardness 4–12°dH and carbonate hardness 3–10°dKH. These are practical rainbowfish-group targets for this genus-level offer. Stability within the range is more useful than repeatedly moving the water towards either end.

Keep ammonia at zero mg/l and nitrite at zero mg/l. Nitrate should not rise by more than 20 mg/l above the normal tap-water level. The tap-water comparison matters: test the source water as well as the aquarium so the nitrate result has a meaningful baseline.

Use the result to make a decision

Our water chemistry guide explains what the main readings mean. After measuring your aquarium, the water matcher helps compare those readings with the working range above.

Compare nitrate with the correct baseline

For example, if the tap water measures 10 mg/l nitrate, the group limit places the aquarium ceiling at 30 mg/l because that is 20 mg/l above the baseline. If the aquarium then measures 35 mg/l, treat the result as above the guidance even though the number may appear moderate on its own. Record both readings and use the difference between them to guide maintenance.

A larger aquarium generally changes more slowly than a small one, which gives you more time to notice and correct a developing water-quality problem. Volume does not replace testing, filtration or maintenance, but it adds useful stability when a social group and other fish share the same system.

Plan space around the whole group

Begin with the social requirement: rainbowfish guidance says to keep a group of at least five, and more is better. A single fish or undersized group will often become stressed, so calculate space and filtration for the whole intended group rather than buying one fish and treating group planning as a later decision.

OATA’s planning benchmarks are at least 45 litres for a shoal of its smallest rainbowfish and at least 120 litres for larger species over 8 cm. Use at least 120 litres as the cautious group benchmark for this unidentified species, while leaving capacity for development and every existing occupant.

Divide the aquarium into useful functions

• Open swimming space: preserve an unobstructed area rather than filling every part of the aquarium with decoration.
• Cover: use live plants where practical, especially for shy fish. Plastic plants and suitable ornaments can provide shelter when live plants are not used.
• Substrate: aquarium gravel or sand is suitable within the group setup described by OATA.
• Filtered volume: allow for the waste produced by the complete group and every existing animal.

Judge a proposed aquarium by usable swimming length, open area, shelter, mature filtration and total stocking, not litres alone. A tall aquarium with little clear horizontal room may offer the same nominal volume as a longer aquarium while giving the group a different amount of swimming space.

Check the complete plan before committing space

Start with at least five Pseudomugil, then add every established occupant to the calculation. A nominally large aquarium may still be a poor choice when decoration removes most of the open area or the existing community already uses that space actively. Conversely, removing unnecessary obstructions can improve swimming room, but it does not increase filtered volume or justify exceeding the aquarium’s biological capacity.

Before combining the group with an established community, list every occupant’s expected adult size and activity. If that comparison leaves uncertainty, ask us for a stocking and compatibility assessment using the aquarium dimensions, test results, current fish and intended Pseudomugil group.

Mature filtration before introducing the group

A working biological filter is essential. RSPCA aquarium welfare guidance explains that fish release toxic ammonia. Beneficial bacteria in a well-established filter convert ammonia into nitrite, which is also toxic, and then into the safer waste product nitrate.

Prepare and mature the filter before adding fish. Our first tropical aquarium guide sets out that preparation in a practical order. Do not judge readiness from clear-looking water alone; confirm that ammonia and nitrite both read zero.

Protect the biological filter

1. Check the filter for blockages as part of routine maintenance.
2. When cleaning is needed, lightly rinse the media in aquarium water removed during a partial water change.
3. Do not rinse established filter media under the tap because chlorine or chloramine may kill beneficial bacteria.
4. Treat replacement tap water with conditioner before it enters the aquarium.
5. Increase the fish population slowly so the bacterial population can adjust as waste and feeding increase.

Adding a full community too quickly can create new tank syndrome: the filter bacteria cannot process the increased waste, allowing ammonia or nitrite to rise. The same risk applies when a mature aquarium receives several new fish and feeding increases sharply. Test after stocking changes rather than assuming an established filter has unlimited capacity.

Use staged checkpoints after stocking

Test after the group is introduced and continue the regular weekly checks while the filter adjusts to the increased waste and feeding. A zero result for ammonia and nitrite supports the next observation period; a detectable result means the stocking plan pauses. Check for a blockage, review feeding and complete the necessary water maintenance before considering another addition.

Use zero ammonia and zero nitrite as decision thresholds. If either is detected, postpone further additions and focus on water quality, filter function and partial water changes. Resume the stocking plan only when the aquarium is stable again.

Filtration and swimming space solve different problems. The filter processes waste, while the aquarium’s dimensions determine how much usable room and shelter the group receives. A powerful filter cannot compensate for an unsuitable social or spatial plan.

Feed a small, controlled portion once daily

Use the OATA rainbowfish diet as group guidance for this unidentified Pseudomugil. Rainbowfish are described as omnivorous and should receive a good-quality flake or granule in the home aquarium. Choose food that the fish can take readily rather than leaving pieces that go uneaten.

Offer only the amount the group can eat within a few minutes, once a day. This time limit is the main portion-control tool. A larger handful is not more nutritious if food remains in the aquarium and breaks down into toxic waste.

Add variety without losing portion control

• Use good-quality flake or granule as the routine food described for the group.
• Small live or frozen daphnia, small bloodworm or tubifex can add variety.
• OATA notes that larger rainbowfish may prefer larger items such as brine shrimp; match every item to what this fish can actually take.
• Count all foods offered at one sitting as part of the same daily portion.

Watch the entire feeding response for those few minutes. Normal interest lets you see that food is being taken, while reduced intake or a lack of interest can be an early health warning. Also notice whether activity or the presence of tank mates prevents part of the group from feeding effectively.

Adjust the amount from what remains

If food is still visible after a few minutes, make the next daily portion smaller. When every item disappears immediately, continue observing rather than automatically adding more; the instruction remains one controlled daily feed. If one fish consistently misses food while others feed, examine social pressure and access instead of increasing the total amount for the whole aquarium.

Overfeeding affects more than body condition. Uneaten food decomposes, adds to the filter’s workload and can contribute to unhealthy ammonia or nitrite. If waste begins to accumulate, reduce the amount at the next daily feed and check the water rather than adding another food in an attempt to encourage appetite.

Keep the routine consistent enough that changes are easy to recognise. A fish that suddenly stops feeding, loses condition or behaves differently needs a water-quality check alongside the wider health observations described below.

Complete the weekly maintenance cycle

Carry out a 25% partial water change at least once a week. Use a siphon to remove solid waste from the gravel or sand, and treat all replacement tap water with conditioner to remove harmful chlorine or chloramine before adding it to the aquarium.

Test the water at least weekly. Record ammonia, nitrite and nitrate, then compare the result with the previous test and the normal tap-water nitrate level. A written sequence makes gradual deterioration easier to recognise than isolated readings.

Use one repeatable checklist

Filter media does not need tap-water washing. When it requires cleaning, rinse it lightly in the old aquarium water removed during the water change. This preserves more of the beneficial bacterial population than exposure to chlorinated or chloraminated tap water.

Review the first month as a sequence

Keep the same testing method, tap-water comparison and maintenance day through the first month. A sequence of zero ammonia and zero nitrite readings is more useful than one isolated result because it shows how the aquarium responds between water changes. Rising nitrate, accumulating debris or reduced filter flow identifies the part of the routine that needs attention before another stocking change.

Maintenance should respond to results without becoming erratic. A routine 25% change is the baseline; any detected ammonia, nitrite or excessive nitrate is a reason to review stocking pace, feeding, waste removal and filter condition together.

Finish by confirming that cover remains secure in position, open swimming room has not become obstructed and the filter is operating normally. These checks link the physical setup with the water-quality routine rather than treating maintenance as water replacement alone.

Acclimatise slowly and observe health changes

Arrange for someone to receive the live-fish parcel so it is not left unattended. Follow the tracking details associated with the order, then use the current delivery and Live Arrival Guarantee policy when the parcel reaches you.

Follow the arrival sequence

1. Receive the parcel in person and do not leave the live fish unattended.
2. Start filming every delivery before the sealed parcel is opened, with the outer box visible.
3. Open the parcel in one continuous take and show the fish still inside the sealed bag before anything is disturbed.
4. Open and inspect the parcel on the day it arrives.
5. Float the bag in the aquarium for 20–30 minutes.
6. Release the fish without pouring the bag water into the aquarium.

Watch for changes rather than one fixed pose

Individual fish naturally vary, so compare behaviour and appearance over time. Warning changes include hanging at the surface, sitting on the bottom, erratic swimming, unusual hiding, altered aggression, darker or paler colour, or gill covers moving faster or slower than normal.

Look closely for white spots, fluffy growths, missing fins or scales, ulcers, bumps, and an increase or decrease in body condition. Reduced food intake or a complete lack of interest in food also deserves attention.

If any of these changes appear, test water quality first because ammonia, nitrite, nitrate and filter performance directly affect fish health. Check recent feeding, maintenance and stocking changes at the same time. Contact us for further guidance about a health change after recording the test results and what you have observed.

Use the first week as a settling checkpoint

Each day, compare swimming, breathing, colour and feeding with the previous observation. Keep the daily ration within the few-minute limit and note whether every fish reaches food. At the weekly checkpoint, test the water, complete the 25% partial change and inspect the filter for blockages before deciding whether the aquarium is ready for any further livestock.

During the first week, keep to the established feeding and weekly testing plan while watching the whole group. Avoid adding more livestock until the aquarium remains stable and the new fish are behaving and feeding consistently.

Screen tank mates by behaviour, scale and water needs

Choose companions by comparing water requirements, expected adult size, activity and feeding behaviour. A shared “community fish” label is not enough: two fish may both be generally easy-going yet make a poor match if one is much more active, occupies the available swimming room or prevents the other from feeding.

OATA notes that some rainbowfish, including threadfin types, need peaceful tank mates that will not nip elongated fins or bully them. It also says active rainbowfish should not be mixed with timid fish or animals much smaller than themselves. Larger rainbowfish are best kept apart from very small fish, even though the group is described as seldom predatory or aggressive towards other species.

Apply each condition to the proposed combination

Work through a proposed match in order

First compare the companion’s routine water range with 22–27°C, pH 6.5–8.0 and 4–12°dH. Next compare expected adult scale. Then check whether either fish is notably timid, highly active, inclined to bully or likely to nip elongated fins. Finally, confirm that the aquarium retains open room and filtered capacity for at least five Pseudomugil plus every existing occupant.

A match fails when one decisive condition conflicts, even if the other checks appear suitable. Shared water values do not cancel a bullying risk, and peaceful behaviour does not correct a water mismatch. This ordered screen prevents one reassuring label from hiding a practical conflict.

The genus-level name leaves genuine variation within Pseudomugil, so use this screening method instead of a universal tank-mate list. A proposed companion is suitable only when all of the relevant conditions align.

Introduce additions slowly after confirming zero ammonia and nitrite. This protects both compatibility observation and biological filtration: a gradual change makes it easier to recognise whether altered behaviour follows the new social combination or a water-quality problem.

Build a social group without relying on sex assumptions

Plan for at least five fish because rainbowfish are shoaling fish and small groups or solitary individuals will often become stressed. More is better when the aquarium has enough filtered volume and open swimming room for the enlarged group.

OATA generally prefers more female rainbowfish than males because males may fight. For this offer, build the aquarium plan around group size and behaviour rather than a precise sex ratio. Do not identify or select sex from colour, fins, body size or a gallery scene.

Choose a workable stocking sequence

• Before the first addition: confirm that the aquarium is mature, filtered and within the stated water range.
• For the intended group: reserve enough swimming space and biological capacity for at least five.
• With an existing community: compare every occupant’s activity, adult scale and feeding behaviour before deciding the total group size.
• After an addition: watch for hiding, altered aggression, erratic swimming, damaged fins or reduced feeding.
• Before adding again: confirm that ammonia and nitrite remain at zero and that the previous social change has settled.

If one fish is repeatedly displaced or cannot feed within the daily few-minute feeding window, treat that as a compatibility warning rather than simply increasing the ration. More food can create waste while leaving the social problem unchanged.

Use plants or suitable ornaments to provide shelter while retaining open swimming space. Cover and open room are complementary: shelter gives a shy fish somewhere to withdraw, while clear space allows the group to move without every route passing through a confined area.

A successful plan therefore combines a proper group, compatible activity levels, usable swimming space, stable water and gradual stocking. No single tank-mate name can replace those checks.

Answer the key questions before choosing

How big does Pseudomugil sp. red neon get?

Treat its eventual size as a planning variable because the name identifies a genus rather than one species. Use OATA’s larger-rainbowfish space category and monitor development rather than treating the size at arrival as the adult length.

What size aquarium does Pseudomugil sp. red neon need?

Use at least 120 litres as the cautious OATA group benchmark, with mature filtration, open swimming room and plants or suitable ornaments for cover. The final aquarium must accommodate at least five fish and every existing occupant.

How many Pseudomugil sp. red neon should I keep?

OATA’s rainbowfish guidance says to keep a group of at least five because solitary fish or undersized groups will often become stressed. More is better when the aquarium has enough filtered capacity and swimming room.

Does Pseudomugil sp. red neon suit beginners?

OATA describes rainbowfish generally as easy to keep, but this fish suits a prepared keeper who can mature the filter, maintain zero ammonia and nitrite, test weekly and plan for a group of at least five.

What does Pseudomugil sp. red neon eat?

OATA’s rainbowfish guidance recommends good-quality flake or granule once daily, limited to what the fish eat within a few minutes. Small live or frozen daphnia, small bloodworm or tubifex can add variety.

What temperature and pH does this fish need?

OATA’s rainbowfish-group guidance gives 22–27°C, pH 6.5–8.0, general hardness 4–12°dH and carbonate hardness 3–10°dKH. Keep ammonia and nitrite at zero and nitrate no more than 20 mg/l above normal tap water.

Is this fish aggressive or likely to nip fins?

OATA describes rainbowfish as seldom predatory or aggressive towards other species, but activity and fin behaviour still need screening. Avoid bullying or fin-nipping companions where elongated fins are present, and avoid mixing highly active fish with timid fish.

Which kinds of animals can live with it?

Choose peaceful fish whose water requirements, adult size and activity align with the group. Avoid fin-nipping or bullying companions where elongated fins are present, and avoid mixing a rainbowfish that develops into a larger species with very small fish.

How does this fish arrive alive in the UK?

Someone must be present to receive the parcel. Film every delivery continuously from the sealed parcel as it is opened, showing the fish still in the sealed bag; then float the bag for 20–30 minutes and release the fish without pouring the bag water into the aquarium.

Consult the scientific and welfare references

• WoRMS taxon details for Pseudomugil — accepted genus, family and order.
• Pseudomugil genus summary — genus-level natural distribution and habitats.
• OATA: How to look after rainbowfish — UK group guidance covering water, shoaling, aquarium planning, feeding, compatibility and maintenance.
• RSPCA aquarium environment guidance — biological filtration and aquarium waste processing.